[PATCH 0/3] make ballooned out pages have a valid mapping at all times

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Hi all,
this patch series limits problems caused by tcp retransmits on NFS when
the original block pages were mapped from a foreign domain and now the
mapping is gone.

It accomplishes the goal by:

1) mapping all ballooned out pages to a "balloon_trade_page";
2) making sure that once a grant is unmapped, the original mapping to
balloon_trade_page is restored atomically.

The first patch accomplishes (1), the second patch is necessary to
introduce a grant_table operation that we can use to do (2). Finally the
last patch uses GNTTABOP_unmap_and_replace to atomically unmap a grant
and restore the original mapping.


Stefano Stabellini (3):
      xen/balloon: set a mapping for ballooned out pages
      xen/grant_table: use the new  GNTTABOP_unmap_and_replace hypercall
      xen/m2p: use GNTTABOP_unmap_and_replace to replace foreign grants with balloon_trade_page

 arch/x86/xen/p2m.c                  |   25 ++++++++++++++++++-------
 drivers/xen/balloon.c               |   10 ++++++++--
 drivers/xen/gntdev.c                |   11 ++---------
 drivers/xen/grant-table.c           |    8 ++++++++
 include/xen/balloon.h               |    1 +
 include/xen/grant_table.h           |    1 +
 include/xen/interface/grant_table.h |    8 +++++---
 7 files changed, 43 insertions(+), 21 deletions(-)

Cheers,

Stefano